Conventional water heaters typically include a water storage tank, a cylindrical outer casing or jacket concentrically positioned around the water storage tank, and an annular cavity disposed therebetween. Foam insulation is typically injected into the annular cavity to significantly reduce the escapement of thermal energy from the water storage tank to the surrounding environment. It is desirable to limit the escapement of thermal energy in an effort to reduce operating costs of the water heater.
For example, U.S. Pat. No. 5,023,031 to West et al., which is incorporated herein by reference in its entirety, discloses a method of insulating a water heater with an expandable foam insulating material. The foam is injected into the annular space between the water tank and the outer jacket. The foam is injected into a sleeve, which acts to confine the foam during its most liquid state, positioned within this space.
U.S. Pat. No. 4,477,399 to Tilton, which is incorporated herein by reference in its entirety, discloses a method for insulating a water heater with foamed insulation comprising the step of inflating a tube in the cavity between the shell and the tank to define a boundary for the cavity into which the insulating material is injected. The device is deflated after the foamed insulation has set in the cavity.
Despite the foregoing improvements, there is a continuing need to further develop methods and apparatuses for insulating electric and gas fired water heaters in the interest of energy conservation.